Alberto Traverso

Demonstration Plant and Expected Performance of an Externally Fired Micro Gas Turbine for Distributed Power Generation

The paper presents the design and development of the first world-wide Externally Fired micro Gas Turbine (EFmGT) demonstration plant based on micro gas turbine technology. The system is particularly useful for exploitation of renewable resources for distributed power and heat generation. The plant has been designed by Ansaldo Ricerche (ARI) s.r.l. and Thermochemical Power Group (TPG) of University of Genoa using TPG in house codes such as TEMP (Thermoeconomic Modular Program) and TRANSEO (TRANSient analysis of energy systems). The plant is based on a recuperated 80 kW micro gas turbine (Elliott TA-80R), and it is under construction at ARI laboratory. The first goal of this plant is the demonstration of the EFmGT system at full and part load operations, mainly from the control point of view. The expected performance (50kW at 16% LHV efficiency) can be improved in the near future using high temperature heat exchangers (a field where ARI has a very long expertise), which should allow the system to operate at the actual micro gas turbine inlet temperature (900–950 °C). In the present paper the design point, off design performance, and part load control system are presented and analysed in depth: it is shown that there are no “forbidden” part load steady state operating points. In a companion paper, where transients of advanced cycles based on mGT technology are discussed, TPG presents the fast and slow transient operation of the EFmGT system.Copyright

Transient Analysis of and Control System for Advanced Cycles Based on Micro Gas Turbine Technology

Microturbines have a less complex mechanical design than large-size gas turbines that should make it possible to fit them with a more straightforward control system. However, these systems have very low shaft mechanical inertia and a fast response to external disturbances, such as load trip, that make this very difficult to do. Furthermore, the presence of the recuperator requires smooth variations to the Turbine Outlet Temperature (TOT), when possible, to ensure reduced thermal stresses to the metallic matrix. This paper, after a brief overview of microturbine control systems and typical transients, presents the expected transient behavior of two advanced cycles: the Externally Fired micro Gas Turbine (EFmGT) cycle, where the aim is to develop a proper control system set-up to manage safe part-load operations at constant rotational speed, and a solar Closed Brayton Cycle (CBC), whose control system has to ensure the maximum efficiency at constant rotational speed and constant Turbine Inlet Temperature (TIT).Copyright